Where are the errors? In the context of operational Assimilation
Posted on December 27, 2017
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The implementation of operational oceanography in the past 15 years has provided many societal benefits and has led to many countries adopting a formal roadmap for providing ocean forecasts. Following on from the GODAE OceanView international schools held in France and in Australia, this school will bring together senior experts and young researchers (pre- and post-doctorate) from across the world and expose them to the latest research in oceanography, specifically how it will impact operational oceanography. In addition to formal lectures, shorter talks by experts in the field will acquaint the participants with a wide range of applications.
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Photo of the week from AGU Fall Meeting in New Orleans, LA
Posted on December 18, 2017
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This week, NRL has been actively engaged at the American Geophysical Union's Fall Meeting in New Orleans. Touted as the largest Earth and space science conference in the world, the Fall Meeting amasses thousands to share scientific research into vital scientific ecosystems. NRL researchers like Drs. Matt Carrier (left) and John Osborne have been participating in many oral presentations and poster sessions throughout the week. Check out some of their research on NRL's Facebook Page!
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Preliminary Investigation of the Impact of Real-time In Situ Data Assimilation in the Navy's Arctic Prediction System
Posted on December 15, 2017
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The U.S. Navy's Arctic prediction systems use a coupled ice-ocean modeling system comprised of the Community Ice CodE (CICE) and the Hybrid Coordinate Ocean Model (HYCOM) with atmospheric forcing from the Navy Global Environmental Model (NAVGEM). Both the Arctic Cap Nowcast/Forecast System (ACNFS) and its replacement the Global Ocean Forecast System 3.1 (GOFS 3.1) assimilate sea surface temperature, ice concentraion, ice edge, and in situ data via the Navy Coupled Ocean Data Assimilation System (NCODA).
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Impact of ice thickness assimilation into the CICEmodel on the short-term ice forecast
Posted on November 13, 2017
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Preliminary data assimilation experiments with the combined NCODA-CICEsystem indicate stability of the developed data assimilation (DA) algorithms. Efficiency of the developed DA procedure depends on the error variance of the ice thickness observations which is rather high (0.5-1.5 m).
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Ocean state and uncertainty forecasts using HYCOM with Local Ensemble Transfer Kalman Filter (LETKF)
Posted on October 12, 2017
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An ensemble forecast system based on the US Navy's operational HYCOM model using Local Ensemble Transfer Kalman Filter (LETKF) technology has been developed for ocean state and uncertainty forecasts. One of the advantages is that the best possible initial analysis states for the HYCOM forecasts are provided by the LETKF which assimilates the Navy's operational observations using ensemble method.
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The impact of ocean surface currents on Sverdrup transport in the mid-latitude North Pacific via the wind stress formulation
Posted on September 14, 2017
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A more complete wind stress formulation takes into account the ocean surface currents,while the conventional wind stress popularly used in ocean circulation models is only a function of 10-mwinds. An analytical solution is derived for the difference of Sverdrup transport induced by using tn instead of tc.
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Mean square slope in SWAN and WAVEWATVH III®; buoy response functions; and limittions of ST1 physics in SWAN
Posted on August 16, 2017
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We evaluate the ability of the SWAN wave model to predict high frequence wave energy, the suitabilty of NDBC buoys for evaluation, and the non-physical impact of swell on windsea growth with ST1/SWAN physics
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Impact of Satellite Observations on Sea Surface Temperature Forecasts via Variational Data Assimilation and Heat Flux Calibration
Posted on August 14, 2017
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Satellite observations are used to guide forecasts of sea surface temperature (SST) through variational data assimilation and heat flux calibration.
In the experiments considered, assimilation is conducted using the Navy Coupled Ocean Data Assimilation (NCODA) in either a standard 3D variational (3DVAR)
or an alternative 4DVAR formulation. Heat flux for the forecasts follows the original operational highest-quality time series or modifies
the flux-determining fields using the Naval Research Laboratory ocean flux (NFLUX) capability.
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Surface Gravity Wave Effect in Turbulent Kinetic Energy Flux across the Air-sea Interface
Posted on July 14, 2017
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The kinetic energy (KE) fluxes into subsurface currents (EFc) is important boundary condition for ocean circulation models. Traditionally, numerical models assume the KE flux from air (EFair) is identical to the KE flux into subsurface currents, that is, no net KE is gained (or lost) by surface waves. In this study, numerical experiments are performed to investigate the KE flux budget across the air-sea interface under both uniform and idealized tropical cyclone winds.
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Providing Ocean Forecasts During Unmanned Warrior 2016
Posted on June 9, 2017
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The model forecasts were used to provide guidance in mission planning for the use of unmanned underwater vehicles during the Unmanned Warrior Exercise 2016.
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The Mississippi River Void
Posted on April 4, 2017
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Evolution of material on the surface of the Mississippi River plume under the action of wind with subsequent trasport to convergence along the sensity front associated with the plume.
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To view animations open the read only powerpoint presentation.
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Gulf of Mexico Extended Range Ensemble Forecasting System
Posted on May 8, 2017
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Implement a capability to provide extended range forecast (60 days) in the Gulf of Mexico and the uncertainty about that forecast in an operational environment.
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The Mississippi River Void
Posted on April 4, 2017
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Evolution of material on the surface of the Mississippi River plume under the action of wind with subsequent transport to convergence along the density front associated with the plume. For animations view using the read only powerpoint presentation.
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US Navy Automated Glider Guidance: NRL Glider Optimization Strategies Overview (GOST)
Posted on March 2, 2017
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Generate an automated Glider Observation Strategy plan using cost functions to identify regions of higher interest, using forecast currents to determine viable paths,and identifying from among these preferred paths that maximize mission-relevant value of glider observations. For animations view using Adobe Acrobat Reader.
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Near-real-time satellite-based bias corrections for ocean model forecast
Posted on Februay 6, 2017
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Atmospheric heat fluxes at the ocean surface are used to force operational ocean models. The required heat fluxes include solar radiation, longwave radiation, sensible heat flux, and latent heat flux. These forcing fields come from atmospheric numerical weather prediction (NWP) models, which often have biases. Monthly or yearly bias correction can be identified and applied to these fields prior to starting the model forecast.
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Verification and Validation of a Navy ESPC Hindcast with Loosly Coupled Data Assimiltion
Posted on January 23, 2017
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The US Navy is developing an Earth System Prediction Capability (ESPC) to provide global environmental information to meet Navy and Department of Defense (DoD) operations and planning needs from the upper atmosphere to under the sea. It will be a fully coupled global atmosphere/ocean/ice/wave/land prediction system providing daily deterministic forecasts out to 16 days at high horizontal and vertical resolution, and daily probabilistic forecasts out to 45 days at lower resolution.
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Ocean Ensemble Forecasting in the Navy Earth System Prediction Capability
Posted on January 17, 2017
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A pair of 20-member ensemble experiments with a global HYCOM
configuration at 1/12° resolution and 32 layers is used to examine the
contribution of the perturbed-observation analysis to the forecast
ensemble spread. The ensemble members are initialized with 20
different 01 Jan states from a 20-year reanalysis. Members are cycled
with the NCODA data assimilation system for 90 d then integrated
over a 90 d forecast with NCEP CSFR forcing.
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High-resolution modeling of local air-sea interaction within the Maritime Continent using COAMPS
Posted on January 11, 2017
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The Maritime Continent (MC) is a region of intense deep atmospheric convection that serves as an important source of forcing for the Hadley and Walker circulations. The convective activity in the MC region spans multiple scales from local mesoscales to regional scales, and impacts equatorial wave propagation, coupled air-sea interaction and intra seasonal oscillations. The complex distribution of islands, shallow seas with fairly small heat storage and deep seas with large heat capacity is challenging to model.
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Impact of Sea Level Rise on Storm Surge and Inundation in the Northwestern Gulf of Mexico
Posted on January 6, 2017
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Investigate what could happen if a Hurricane Ike makes landfall at Galveston TX, combined with increased sea-level rise. Study effect of 0.5m, 1.0m 2.0m rise in mean sea level.
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